Phylum

Mollusca(5 Classes) Policemen censor gals in scant bikinis!

Polyplacophora – Many plates on a foot

Cephalopoda – Head foot

Gastropoda – Stomach

Scaphopoda – Tusk shell

Bivalvia – Hatchet foot

foot

Typical questions for Mollusca

How many of these specimens posses a radula?

Which ones are filter feeders?

Which have undergone torsion? Detorsion?

What is the function of the mantle?

Name a class used for currency

Which specimens lungs vs. gills? Just have think of which live on land vs. in water……

Oldest part of a univalve shell? Bivalve?

Answers…maybe

• Gastropods, Cephalopoda, Mono-, A- & Polyplacophora • Bivalvia (Scaphopoda….have a captacula)• Gastropods Opisthobranchia (sea hares & sea slugs)

and the land slugs of the Pulmonata• Mantle secretes the shell• Scaphopoda• Pulmonata – their name gives this away• Apex for Univalve, Umbo for bivalve but often the terms

are used interchangeably

Chitons radula, 8 plates

Class Polyplacophora

MantleAnus Gills in

mantle cavity

Radula in mouth

Head

Class Cephalopoda - Octopuses, Squid, Nautilus,Cuttlefish…beak, pen, ink sac, chromatophores,jet propulsion……….dissection.

My tentacles (2) & arms are derived from the Gastropod foot

GastropodaWORDS TO KNOW:

snails, conchs, torsion, coiling, radula, operculum & egg sac

Subclass Prosobranchia Aquatic

–marine.

Generally they have thick pointed shells, with spines. Many have opercula.

Subclass

Pulmonata Aquatic –freshwater. Shells are thin, rounded, with no spines, ridges or opercula.

Apex

…….it issomething from Class Gastropoda

(…or your roommate!)

Subclass PulmonataSlug

Subclass Opisthobranchia

Nudibranch

Detorsion…

If something looks strange, chances are….

Class Gastropoda

‘POP’Subclass Prosobranchia

- Aquatic snails (“shells”)

- Have gills

Subclass Opisthobranchia- Marine

- Have gills

- Nudibranchs / Sea slugs / Sea hares

- Mantle cavity & shell reduced or absent

Subclass Pulmonata- Terrestrial Slugs and terrestrial snails

- Have lungs

Sinistral Dextral

Class Scaphopoda - “tusk shells”

Currency for Wampum Indians. Head in sand. Respire through mantle (no gills.) Captacula

for feeding on foramniferans

ClaBivalvia or Pelecypoda - clams, scallops etc.filter feeders, bivalved shells…… dissection

D

VAP

Name of oldest part?

ClaBivalvia or Pelecypoda - clams, scallops etc.filter feeders, bivalved shells…… dissection

D

VAP

Umbo

Path of water (O2 )

Mouth

VentricleBulbus

arteriosus

Heart

Foot

Gills

Mantle

Excurrent

& Incurrent siphon –

(hairs & papullae)

Very

Schematic Diag. of a Clam Dissection

Gills or ctenidium

–

Each = 2 demibranchs

Anterior (Umbo)

Posterior (siphons)

Dorsal (hinge)

Ventral

Auricle

Visceral Mass

Area of gastric & /digestive glands

Adductor muscles